This project has continued to be devoted primarily to the metabolism of the visual cells and pigment epithelium in experimental animals, studied by the techniques of conventional and electron microscopy coupled with autoradiography. Major emphasis is on renewal processes. In the forthcoming year, projects will be pursued which focus attention on the daily rhythm of autophagy and other events visible by electron microscopy in the inner segments of frog visual cells, and on the daily rhythm of RNA synthesis in the nuclei of goldfish and frog visual cells, exposed to tritiated cytidine in vitro and subsequently analyzed by autoradiography.